KR20240068664A - Adhesive compositions, adhesive sheets, and joints - Google Patents

Abstract

The purpose of the present invention is to provide an adhesive composition whose adhesive strength is sufficiently reduced by application of voltage even after storage in a high-temperature, high-humidity environment. The present invention is a pressure-sensitive adhesive composition containing a first polymer and an ionic liquid, comprising the first polymer as a base polymer and further comprising a second polymer having a glass transition temperature Tg of 40 to 180°C. It's about.

Description

Adhesive compositions, adhesive sheets, and joints

The present invention relates to an adhesive composition, an adhesive sheet containing an adhesive layer formed from the adhesive composition, and a bonded body of the adhesive sheet and an adherend.

In the electronic component manufacturing process, etc., there is an increasing demand for rework to improve yield and recycling to disassemble and recover components after use. In order to meet such requests, double-sided adhesive sheets that have a certain adhesive force and a certain peelability are sometimes used when joining members in an electronic component manufacturing process or the like.

A double-sided adhesive sheet that realizes the above-described adhesive strength and peelability, using an ionic liquid consisting of a cation and an anion as a component forming the adhesive composition, and peeling off by applying a voltage to the adhesive layer (electrical peel type) adhesive sheet) is known (Patent Document 1).

In the electrically peelable adhesive sheet of Patent Document 1, by application of voltage, cations of the ionic liquid move on the cathode side and reduction occurs, and anions of the ionic liquid move and oxidation occurs on the anode side, reducing the adhesive strength of the adhesive interface. It is thought that it becomes weak and becomes easy to peel.

In addition, in Patent Document 2, for example, an adhesive composition whose adhesive strength is sufficiently reduced by application of voltage even in a low-humidity environment such as winter is studied.

International Publication No. 2017/064918 Japanese Patent Publication No. 2020-164778

The electrically peelable adhesive sheet is preferably one that firmly bonds members when no voltage is applied and can be peeled off with little force when voltage is applied. Therefore, in an electrically peelable adhesive sheet, it is preferable that the rate of decrease in adhesive strength due to application of voltage is large.

However, in conventional adhesive compositions, the rate of decline in adhesive strength due to application of voltage sometimes decreases with time. And, as a result of the present inventors' examination, a new problem was found that the rate of decline in adhesive strength due to application of voltage becomes small after storage in a high-humidity and high-temperature environment such as summer.

The present invention was completed in consideration of the above, and is a pressure-sensitive adhesive composition capable of forming an adhesive layer with excellent wet-heat stability, the adhesive strength of which is sufficiently reduced by application of voltage even after storage in a high-temperature, high-humidity environment, and a pressure-sensitive adhesive composition formed from the pressure-sensitive adhesive composition. The object is to provide an adhesive sheet provided with an adhesive layer.

According to the present inventors' examination, the reason that the rate of decline in adhesive strength due to voltage application decreases after storage in a high temperature and high humidity environment is that the viscosity of the adhesive layer increases in a high temperature and high humidity environment, making it difficult for cations and anions of the ionic liquid to move. I could see that it was due to losing.

As a result of further examination by the present inventors, the following findings were obtained.

It was found that by further containing a polymer with a Tg of 40 to 180°C in addition to the base polymer, the electrical peelability was good even after storage in a high temperature and high humidity environment, that is, the rate of decrease in adhesive strength due to application of voltage was large.

The means for solving the above problems are as follows.

〔One〕

An adhesive composition containing a first polymer and an ionic liquid,

Comprising the first polymer as a base polymer,

An adhesive composition further comprising a second polymer having a glass transition temperature (Tg) of 40 to 180°C.

〔2〕

The pressure-sensitive adhesive composition according to [1], wherein the HSP value difference between the first polymer and the second polymer is 0 to 3.

〔3〕

The adhesive composition according to [1], wherein the second polymer contains an organic polymer compound, and the content of the organic polymer compound in the second polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer.

〔4〕

The anion of the ionic liquid contains at least one selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion, [1] The adhesive composition described in .

〔5〕

The adhesive composition according to [1], wherein the cation of the ionic liquid contains at least one member selected from the group consisting of nitrogen-containing onium cation, sulfur-containing onium cation, and phosphorus-containing onium cation.

〔6〕

The adhesive composition according to [1], wherein the content of the ionic liquid is 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the first polymer.

〔7〕

The first polymer contains at least one member selected from the group consisting of a polyester polymer, a urethane polymer, and an acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond. [1] The adhesive composition described.

〔8〕

The adhesive composition according to [1], wherein the second polymer contains a tackifying resin.

〔9〕

The adhesive composition according to [8], wherein the softening point of the tackifying resin is 100°C or higher.

〔10〕

The adhesive composition according to [8], wherein the content of the tackifying resin is 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer.

〔11〕

The adhesive composition according to [8], wherein the tackifying resin is a terpene-based tackifying resin or a rosin-based tackifying resin.

〔12〕

The adhesive composition according to [1], for electrical peeling.

〔13〕

[1] A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [12].

〔14〕

Equipped with the adhesive sheet described in [13] and a conductive material,

A bonded body in which the adhesive layer is adhered to the conductive material.

The adhesive strength of the adhesive composition of the present invention is sufficiently reduced by application of voltage even after storage in a high-temperature, high-humidity environment.

1 is a cross-sectional view showing an example of the adhesive sheet of the present invention.
Figure 2 is a cross-sectional view showing an example of the laminated structure of the pressure-sensitive adhesive sheet of the present invention.
Figure 3 is a cross-sectional view showing another example of the laminated structure of the pressure-sensitive adhesive sheet of the present invention.
Figure 4 is a cross-sectional view showing an outline of the 180° peel test method in the Example.

Hereinafter, modes for carrying out the present invention will be described in detail. In addition, the present invention is not limited to the embodiment described below.

[Adhesive composition]

The pressure-sensitive adhesive composition according to an embodiment of the present invention is a pressure-sensitive adhesive composition containing a first polymer and an ionic liquid, comprising the first polymer as a base polymer and further comprising a second polymer having a Tg of 40 to 180°C. Includes.

The adhesive composition according to the embodiment of the present invention is preferably used for electrical peeling.

Hereinafter, the adhesive composition will be described.

In addition, in this specification, the first polymer may be referred to as a “base polymer.”

The base polymer in the adhesive composition according to the present embodiment refers to the main component in the polymer contained in the adhesive composition. In addition, in this specification, the “main component” refers to a component contained in excess of 50% by mass, unless otherwise specified.

In addition, in this specification, the adhesive force when no voltage is applied may be referred to as “initial adhesive force.”

In addition, among the components contained in the adhesive composition, a composition consisting of components other than the ionic liquid may be referred to as an “ion liquid-free adhesive composition.”

In addition, the pressure-sensitive adhesive layer formed from the ionic liquid-free pressure-sensitive adhesive composition may be referred to as the “ion liquid-free pressure-sensitive adhesive layer.”

In addition, the property that the adhesive strength decreases by applying voltage is sometimes referred to as “electrical peelability,” and the property in which the adhesive strength decreases due to voltage application is high is sometimes referred to as “excellent electrical peelability.”

<Ingredients of adhesive composition>

(First polymer (base polymer))

The pressure-sensitive adhesive composition according to the embodiment of the present invention contains a first polymer as a base polymer. In the embodiment of the present invention, the base polymer is not particularly limited as long as it is a general organic polymer compound, for example, a polymer or partial polymer of monomers. The monomer may be one type of monomer, or may be a mixture of two or more types of monomers. Additionally, the partially polymerized product means a polymerized product in which at least a portion of the monomer or monomer mixture is partially polymerized.

The first polymer in the embodiment of the present invention is generally used as an adhesive and is not particularly limited as long as it has adhesiveness. For example, acrylic polymer, rubber polymer, vinyl alkyl ether polymer, silicone polymer, poly Examples include ester-based polymers, polyamide-based polymers, urethane-based polymers, fluorine-based polymers, and epoxy-based polymers.

The above polymers can be used individually or in combination of two or more types.

The first polymer in the embodiment of the present invention is at least one selected from the group consisting of polyester polymers, urethane polymers, and acrylic polymers having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond. It is desirable to include it. Polyester-based polymers and urethane-based polymers have hydroxyl groups at their terminals that are easily polarized, and acrylic polymers having carboxyl groups, alkoxy groups, hydroxyl groups and/or amide bonds have carboxyl groups, alkoxy groups, hydroxyl groups and/or Alternatively, since the amide bond is easily polarized, by using these polymers, an adhesive layer that exhibits excellent adhesive strength when no voltage is applied can be obtained.

The total content of the base polymer in all polymers contained in the adhesive composition according to the embodiment of the present invention is preferably 60% by mass or more, and more preferably 80% by mass or more.

In particular, in order to increase cost, productivity, and initial adhesion, the polymer in the embodiment of the present invention is preferably an acrylic polymer, and is an acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond. It is more preferable that it is a polymer.

That is, the pressure-sensitive adhesive composition according to the embodiment of the present invention is preferably an acrylic pressure-sensitive adhesive composition containing an acrylic polymer as a base polymer.

The acrylic polymer preferably contains a monomer unit derived from an alkyl (meth)acrylate (formula (1) below) having an alkyl group having 1 to 14 carbon atoms. Such monomer units are desirable for obtaining high initial adhesion. In addition, in order to improve the adhesive strength and electrical peelability of the resulting pressure-sensitive adhesive layer without applying voltage, the carbon number of the alkyl group R ^b in the following formula (1) is preferably small, especially preferably 8 or less, and more preferably 4 or less. do.

CH ₂ =C(R ^a )COOR ^b (1)

[R ^a in formula (1) is a hydrogen atom or a methyl group, and R ^b is an alkyl group having 1 to 14 carbon atoms]

Examples of (meth)acrylic acid alkyl esters having an alkyl group having 1 to 14 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, 1,3-dimethylbutyl acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2 -Ethylbutyl (meth)acrylate, heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate rate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, and n- Tetradecyl (meth)acrylate, etc. can be mentioned. Among them, n-butylacrylate, 2-ethylhexyl acrylate, and isononyl acrylate are preferable. (meth)acrylic acid alkyl esters having an alkyl group of 1 to 14 carbon atoms can be used individually or in combination of two or more types.

The ratio of the (meth)acrylic acid alkyl ester having an alkyl group of 1 to 14 carbon atoms relative to the total monomer components (100 mass%) constituting the acrylic polymer is not particularly limited, but is preferably 70 mass% or more, more preferably It is 80 mass% or more, more preferably 85 mass% or more. When the proportion of acrylic polymer is 70% by mass or more, it becomes easy to obtain a large initial adhesive force.

Acrylic polymers include monomer units derived from (meth)acrylic acid alkyl esters having an alkyl group of 1 to 14 carbon atoms for the purpose of modifying cohesion, heat resistance, crosslinking properties, etc., as well as monomer units derived from polar group-containing monomers that can be copolymerized with this. It is preferred that it contains monomer units. Monomer units can provide crosslinking points and are preferred for obtaining large initial adhesion. Additionally, from the viewpoint of improving adhesion and electrical peelability when no voltage is applied, it is preferable to include a monomer unit derived from a polar group-containing monomer.

Examples of polar group-containing monomers include carboxyl group-containing monomers, alkoxy group-containing monomers, hydroxyl group-containing monomers, cyano group-containing monomers, vinyl group-containing monomers, aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, and amino groups. monomers containing epoxy groups, vinyl ether monomers, N-acryloylmorpholine, monomers containing sulfo groups, monomers containing phosphoric acid groups, and monomers containing acid anhydride groups. Among them, because of their excellent cohesiveness, carboxyl group-containing monomers, alkoxy group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers are preferable, and carboxyl group-containing monomers are particularly preferable. Carboxyl group-containing monomers are particularly preferred for obtaining high initial adhesion. The polar group-containing monomer can be used individually or in combination of two or more types.

Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. You can. In particular, acrylic acid is preferred. Carboxyl group-containing monomers can be used individually or in combination of two or more types.

Examples of the alkoxy group-containing monomer include a methoxy group-containing monomer and an ethoxy group-containing monomer. Examples of the methoxy group-containing monomer include 2-methoxyethyl acrylate.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl. (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, N-methylol (meth)acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. . In particular, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferable. Hydroxyl group-containing monomers can be used individually or in combination of two or more types.

Amide group-containing monomers include, for example, acrylamide, methacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, and N,N-diethylacrylamide. , N,N-diethyl methacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, and diacetone acrylamide. You can. Amide group-containing monomers can be used individually or in combination of two or more types.

Examples of cyano group-containing monomers include acrylonitrile and methacrylonitrile.

Examples of the vinyl group-containing monomer include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate, and vinyl acetate is particularly preferable.

Examples of aromatic vinyl monomers include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrenes.

Examples of imide group-containing monomers include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

Examples of amino group-containing monomers include aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth)acrylate.

Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether.

Examples of vinyl ether monomers include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

The ratio of the polar group-containing monomer to the total monomer components (100 mass%) constituting the acrylic polymer is preferably 0.1 mass% or more and 35 mass% or less. The upper limit of the ratio of the polar group-containing monomer is more preferably 25 mass%, further preferably 20 mass%, and the lower limit is more preferably 0.5 mass%, further preferably 1 mass%, and particularly preferred. Typically, it is 2% by mass. If the ratio of the polar group-containing monomer is 0.1% by mass or more, cohesive force becomes easy to obtain, making it difficult for glue to remain on the surface of the adherend after peeling off the adhesive layer, and electrical peelability is improved. Moreover, if the ratio of the polar group-containing monomer is 35% by mass or less, it becomes easy to prevent the adhesive layer from excessively adhering to the adherend and causing heavy peeling. In particular, when it is 2% by mass or more and 20% by mass or less, it becomes easy to achieve both peelability to the adherend and adhesion between the adhesive layer and other layers.

In addition, the monomer component constituting the acrylic polymer may contain a polyfunctional monomer in order to introduce a crosslinked structure into the acrylic polymer and make it easier to obtain the necessary cohesive force.

Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1 , 6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinylbenzene, and N, N'-methylenebisacrylamide, etc. can be mentioned. Polyfunctional monomers can be used individually or in combination of two or more types.

The content of the polyfunctional monomer relative to the total monomer components (100 mass%) constituting the acrylic polymer is preferably 0.1 mass% or more and 15 mass% or less. The upper limit of the content of the polyfunctional monomer is more preferably 10 mass%, and the lower limit is more preferably 3 mass%. If the content of the polyfunctional monomer is 0.1% by mass or more, the flexibility and adhesiveness of the adhesive layer can easily be improved, so it is preferable. If the content of the polyfunctional monomer is 15% by mass or less, the cohesive force does not increase too much and it becomes easy to obtain appropriate adhesiveness.

Polyester-based polymers typically include polyhydric carboxylic acids such as dicarboxylic acids and their derivatives (hereinafter also referred to as “polyhydric carboxylic acid monomers”) and polyhydric alcohols such as diols and their derivatives (hereinafter referred to as “polyhydric alcohol monomers”) 」) is a polymer with a condensed structure.

The polyhydric carboxylic acid monomer is not particularly limited, but examples include adipic acid, azelaic acid, dimer acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxyl. Acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenyl succinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride Maleic acid, maleic anhydride, itaconic acid, citraconic acid, and derivatives thereof can be used.

Polyhydric carboxylic acid monomers can be used individually or in combination of two or more types.

The polyhydric alcohol monomer is not particularly limited, but examples include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-butanediol, 1, 3-Butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2 , 4-trimethyl-1,5-pentanediol, 2-ethyl-2-butylpropanediol, 1,9-nonanediol, 2-methyloctanediol, 1,10-decanediol, and their derivatives can be used. there is.

Polyhydric alcohol monomers can be used individually or in combination of two or more types.

Additionally, the first polymer according to the embodiment of the present invention may contain an ionic polymer. An ionic polymer is a polymer that has an ionic functional group. When the first polymer contains an ionic polymer, electrical peelability is improved. When the first polymer contains an ionic polymer, the content of the ionic polymer is preferably 0.05 parts by mass or more and 2 parts by mass or less with respect to 100 parts by mass of the first polymer.

In an embodiment of the present invention, the first polymer can be obtained by (co)polymerizing a monomer component. The polymerization method is not particularly limited, and includes solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization (active energy ray polymerization). In particular, from the viewpoint of cost and productivity, the solution polymerization method is preferable. When copolymerized, the first polymer may be any of random copolymers, block copolymers, alternating copolymers, and graft copolymers.

The solution polymerization method is not particularly limited, and includes a method in which a monomer component, a polymerization initiator, etc. are dissolved in a solvent and heated to polymerize the solution to obtain a polymer solution containing the first polymer.

As the solvent used in the solution polymerization method, various general solvents can be used. Examples of such solvents (polymerization solvents) include aromatic hydrocarbons such as toluene, benzene, and xylene; Ester such as ethyl acetate and n-butyl acetate; Aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. Solvents can be used individually or in combination of two or more types.

The amount of solvent used is not particularly limited, but is preferably 10 parts by mass or more and 1000 parts by mass or less relative to all monomer components (100 parts by mass) constituting the first polymer. The upper limit of the amount of solvent used is more preferably 500 parts by mass, and the lower limit is more preferably 50 parts by mass.

The polymerization initiator used in the solution polymerization method is not particularly limited, and includes peroxide-based polymerization initiators, azo-based polymerization initiators, and the like. The peroxide-based polymerization initiator is not particularly limited, but includes peroxycarbonate, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, and peroxyester, and more specifically, peroxide-based polymerization initiator. is benzoyl peroxide, t-butylhydroperoxide, di-t-butyl peroxide, t-butylperoxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3, 5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane. The azo polymerization initiator is not particularly limited, but includes 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2,4 -dimethylvaleronitrile), 2,2'-azobis(2-methylpropionic acid)dimethyl, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1'- Azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), 4,4'-azobis-4-cyanovalerian acid, 2,2'- Azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azo Bis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine)hydrochloride, and 2,2'-azobis[N-(2-carboxylic acid) Ethyl)-2-methylpropionamidine] hydrate, etc. can be mentioned. The polymerization initiator can be used individually or in combination of two or more types.

The amount of the polymerization initiator used is not particularly limited, but is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to all monomer components (100 parts by mass) constituting the first polymer. The upper limit of the amount of polymerization initiator used is more preferably 3 parts by mass, and the lower limit is more preferably 0.05 parts by mass.

In the solution polymerization method, the heating temperature when heating and polymerizing is not particularly limited, but is, for example, 50°C or more and 80°C or less. The heating time is not particularly limited, but is, for example, 1 hour or more and 24 hours or less.

The weight average molecular weight of the first polymer is not particularly limited, but is preferably 100,000 or more and 5,000,000 or less. The upper limit of the weight average molecular weight is more preferably 4 million, even more preferably 3 million, and the lower limit is more preferably 200,000, and even more preferably 300,000. If the weight average molecular weight is 100,000 or more, the cohesive force becomes small, and the problem of glue remaining on the surface of the adherend after peeling off the adhesive layer can be effectively suppressed. Moreover, if the weight average molecular weight is 5 million or less, the problem that the wettability of the surface of the adherend after peeling off the adhesive layer becomes insufficient can be effectively suppressed.

The weight average molecular weight is obtained by measuring by the gel permeation chromatography (GPC) method. More specifically, for example, using the product name "HLC-8220GPC" (manufactured by Tosoh Corporation) as a GPC measuring device, It can be measured under the following conditions and calculated using standard polystyrene conversion values.

(Conditions for measuring weight average molecular weight)

・Sample concentration: 0.2% by mass (tetrahydrofuran solution)

·Sample injection volume: 10 μL

·Sample column: TSKguardcolumn SuperHZ-H (1 piece) + TSKgel SuperHZM-H (2 pieces)

・Reference column: TSKgel SuperH-RC (1 piece)

·Eluent: Tetrahydrofuran (THF)

·Flow rate: 0.6 mL/min

Detector: Differential refractometer (RI)

·Column temperature (measurement temperature): 40℃

The glass transition temperature (Tg) of the first polymer is not particularly limited, but is preferably 0°C or lower because it can suppress the decline in initial adhesive strength, more preferably -10°C or lower, and even more preferably - It is below 20℃. Moreover, -40°C or lower is particularly preferable because the rate of decline in adhesive strength due to voltage application is particularly high, and most preferably -50°C or lower.

The composition of the monomer component is set so that the glass transition temperature (hereinafter also referred to as “glass transition temperature of the polymer”) determined by Fox's equation based on the composition of the monomer component is -75 ℃ or more and -10 ℃ or less. It can be. In some embodiments, the glass transition temperature (Tg) of the polymer (e.g., an acrylic polymer, typically an acrylic polymer) is suitably -15°C or lower, preferably -20°C or lower, and -25°C or lower. It is more preferable that it is -30°C or lower, and it may be -40°C or lower (for example, -55°C or lower). When the Tg of the polymer is lowered, the adhesion of the pressure-sensitive adhesive layer to the base layer and to the adherend generally tends to improve.

Here, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by independently polymerizing each of the monomers constituting the copolymer, as shown below.

1/Tg = Σ(Wi/Tgi)

In addition, in the formula of Fox, Tg is the glass transition temperature of the copolymer (unit: K), Wi is the weight fraction of monomer i in the copolymer (copolymerization ratio based on weight), and Tgi is the homopolymer of monomer i. Indicates the glass transition temperature of the polymer (unit: K).

As the glass transition temperature of the homopolymer used to calculate Tg, the value described in known data is used. For example, for the monomers illustrated below, the following values are used as the glass transition temperature of the homopolymer of the monomer.

n-butylacrylate -55℃

Methyl methacrylate 105℃

Methyl acrylate 8℃

Cyclohexyl methacrylate 66℃

N-vinyl-2-pyrrolidone 54℃

4-Hydroxybutylacrylate -40℃

Isobornyl methacrylate 180℃

acrylic acid 106℃

Acryloylmorpholine (ACMO) 145℃

For the glass transition temperature of homopolymers of monomers other than those exemplified above, the values described in “Polymer Handbook” (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple types of values are described in this document, the highest value is adopted.

For monomers for which the glass transition temperature of homopolymers is not described in the Polymer Handbook, the value obtained by the following measurement method is used (see Japanese Patent Application Laid-Open No. 2007-51271). Specifically, 100 parts by weight of monomer, 0.2 parts by weight of azobisisobutyronitrile, and 200 parts by weight of ethyl acetate as a polymerization solvent were added to a reactor equipped with a thermometer, a stirrer, a nitrogen introduction pipe, and a reflux cooling pipe, and nitrogen gas was added. Stir for 1 hour while circulating. After removing oxygen in the polymerization system in this way, the temperature is raised to 63°C and reaction is carried out for 10 hours. Next, it is cooled to room temperature to obtain a homopolymer solution with a solid content concentration of 33% by mass. Next, this homopolymer solution is casted onto a release liner and dried to prepare a test sample (sheet-like homopolymer) with a thickness of about 2 mm. This test sample was punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and subjected to shear strain at a frequency of 1 Hz using a viscoelasticity tester (ARES, manufactured by Rheometrics) in a temperature range of -70 to 150°C. , viscoelasticity is measured in shear mode at a temperature increase rate of 5°C/min, and the peak top temperature of tanδ is taken as the Tg of the homopolymer.

The content of the first polymer in the adhesive composition according to the embodiment of the present invention is preferably 50% by mass or more and 99.9% by mass or less with respect to the total amount (100% by mass) of the adhesive composition, and the upper limit is more preferably It is 99.5 mass%, more preferably 99 mass%, and the lower limit is more preferably 60 mass%, and even more preferably 70 mass%.

(second polymer)

The pressure-sensitive adhesive composition according to the embodiment of the present invention further contains a second polymer having a glass transition temperature (Tg) of 40 to 180°C.

In the pressure-sensitive adhesive composition according to the embodiment of the present invention, the second polymer needs to have a glass transition temperature (Tg) of 40 to 180°C. Additionally, it may be different from the first polymer.

The pressure-sensitive adhesive composition according to the embodiment of the present invention contains a second polymer having a glass transition temperature (Tg) of 40 to 180° C., thereby obtaining the effect of improving the elastic modulus, exhibiting excellent adhesion when no voltage is applied, and maintaining high temperature and high humidity. Even after storage in an environment, an adhesive layer with excellent wet-and-heat stability can be formed, with adhesive strength sufficiently reduced by application of voltage.

The glass transition temperature (Tg) of the second polymer is preferably 40°C or higher, more preferably 50°C or higher, further preferably 60°C or higher, and particularly preferably 70°C or higher from the viewpoint of adhesive properties. Also, from the viewpoint of adhesive properties, it needs to be 180°C or lower, more preferably 160°C or lower, more preferably 140°C or lower, even more preferably 120°C or lower, and especially preferably 100°C or lower.

The glass transition temperature (Tg) in the second polymer can be calculated by the same method as the glass transition temperature (Tg) in the first polymer.

In addition, the glass transition temperature (Tg) in the second polymer can be adjusted depending on the type or compounding amount of the monomer constituting the second polymer.

In the embodiment of the present invention, the second polymer is not particularly limited as long as Tg satisfies the above-mentioned specific range, and general organic polymer compounds can be used, and examples thereof include polymers or partial polymers of monomers. The monomer may be one type of monomer or a mixture of two or more types of monomers. In addition, the above-mentioned partially polymerized product means a polymerized product in which one or two or more components of a monomer or monomer mixture are partially polymerized.

Moreover, the second polymer may be one having tackiness or may be a tackifying resin. The second polymer preferably contains a tackifying resin, and more preferably contains a tackifying resin in addition to the organic polymer compound. It is preferable that the second polymer contains a tackifier resin because it is possible to form a pressure-sensitive adhesive layer with a further improved rate of adhesion reduction due to application of voltage after storage in a high-temperature, high-humidity environment.

Organic polymer compounds contained in the second polymer include, for example, acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine polymers, and epoxy polymers. etc. can be mentioned.

In addition, in this specification, the organic polymer compound in the second polymer refers to a compound that is a polymer or partial polymer of monomers, and refers to a component different from the tackifying resin and the first polymer.

Moreover, examples of the tackifying resin include rosin-based tackifying resins such as rosin resin, rosin phenol resin, and rosin ester resin; Hydrogenated rosin-based tackifying resin obtained by hydrogenating these rosin-based resins; Terpene-based tackifying resins such as terpene-based resin, terpene phenol-based resin, and aromatic modified terpene-based resin; Hydrogenated terpene-based tackifying resin obtained by hydrogenating these terpene-based resins; C5-based petroleum resin obtained by copolymerizing C5 fractions such as pentene, isoprene, piperine, and 1,3-pentadiene produced by thermal decomposition of petroleum naphtha, and hydrogenated petroleum tackifying resin of this C5-based petroleum resin; C9-based petroleum resin obtained by copolymerizing C9 fractions such as indene, vinyltoluene, α-methylstyrene, and β-methylstyrene produced by thermal decomposition of petroleum naphtha, and hydrogenated petroleum tackifier resin of this C9-based petroleum resin; Phenolic tackifying resin; Hydrocarbon-based tackifying resins, etc. can be mentioned.

Examples of the phenol-based tackifying resin include terpene phenol resin, hydrogenated terpene phenol resin, alkyl phenol resin, rosin phenol resin, and xylene formaldehyde-based resin.

Terpene phenol resin refers to a polymer containing a terpene residue and a phenol residue, and includes a copolymer of terpenes and phenol compounds (terpene-phenol copolymer resin) and a phenol-modified homopolymer or copolymer of terpenes (phenol It is a concept that includes both modified terpene resins. Terpenes constituting such terpene phenol resin include, for example, monoterpenes such as α-pinene, β-pinene, and limonene (including d-form, l-form, and d/l-form (dipentene)) etc. can be mentioned.

The hydrogenated terpene phenol resin refers to a hydrogenated terpene phenol resin having a structure obtained by hydrogenating such a terpene phenol resin, and is sometimes called a hydrogenated terpene phenol resin.

Alkylphenol resin is a resin (oil-based phenol resin) obtained from alkylphenol and formaldehyde. Examples of the alkylphenol resin include novolac type and resol type.

Examples of the rosin phenol resin include phenol-modified products of rosins or various rosin derivatives (including rosin esters, unsaturated fatty acid-modified rosins, and unsaturated fatty acid-modified rosin esters). Examples of rosin phenol resins include rosin phenol resins obtained by adding phenol to rosins or various rosin derivatives using an acid catalyst and subjecting them to thermal polymerization.

Examples of the terpene-based tackifying resin include terpene resin, terpene phenol resin, styrene-modified terpene resin, aromatic-modified terpene resin, and hydrogenated terpene resin.

Terpene resins include polymers of terpenes (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene, and dipentene. Examples of homopolymers of one type of terpene include α-pinene polymer, β-pinene polymer, and dipentene polymer.

The concept of rosin-based tackifying resin includes both rosins and rosin derivative resins.

Examples of rosins include unmodified rosin (raw rosin) such as gum rosin, wood rosin, and tall oil rosin; Modified rosin obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, etc. (hydrogenated rosin, disproportioned rosin, polymerized rosin, other chemically modified rosin, etc.); etc. can be mentioned.

Examples of the rosin derivative resin include rosin esters such as unmodified rosin esters that are esters of unmodified rosin and alcohols, and modified rosin esters that are esters of modified rosin and alcohols; Unsaturated fatty acid-modified rosins obtained by modifying rosins with unsaturated fatty acids; Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; Rosin alcohols obtained by reducing the carboxyl groups of rosins and rosin derivative resins (rosin esters, unsaturated fatty acid-modified rosins, unsaturated fatty acid-modified rosin esters, etc.); Rosin phenols; Metal salts thereof; etc. can be mentioned.

Rosin esters include, for example, methyl esters of unmodified rosin or modified rosin (e.g., hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), triethylene glycol ester, glycerin ester, pentaerythritol ester, Maleic acid ester, etc. can be mentioned.

Hydrocarbon-based tackifying resins include, for example, aliphatic hydrocarbon resins, aromatic hydrocarbon resins (e.g., styrene-based resins, xylene-based resins, etc.), aliphatic cyclic hydrocarbon resins, and aliphatic/aromatic petroleum resins ( styrene-olefin-based copolymers, etc.), aliphatic/alicyclic-based petroleum resins, hydrogenated hydrocarbon resins, coumarone-based resins, and coumarone-indene-based resins.

Among these, terpene-based tackifying resin or rosin-based tackifying resin is preferable. The tackifying resin may be used individually or in combination of two or more types.

The softening point of the tackifying resin is preferably 100°C or higher, more preferably 110°C or higher, further preferably 120°C or higher, and most preferably 130°C or higher. By setting the softening point to 100°C or higher, the cohesion of the resin can be improved, and as a result, the adhesive strength when no voltage is applied, that is, the initial adhesive strength, can be further improved. Moreover, the upper limit of the softening point of the tackifying resin is preferably 200°C or lower, more preferably 180°C or lower, further preferably 160°C or lower, and most preferably 140°C or lower.

The content of the tackifying resin in the adhesive composition according to the embodiment of the present invention is preferably 1 to 50 parts by mass, more preferably 1 to 30 parts by mass, and 1 to 20 parts by mass with respect to 100 parts by mass of the first polymer. It is more preferable, and it is most preferable that it is 1 to 15 parts by mass. By setting the content to 1 part by mass or more per 100 parts by mass of the first polymer, the effect of adding a tackifier, that is, the effect of achieving both initial adhesive force and electrical peelability, is easy to be obtained. Moreover, by setting the content to 50 parts by mass or less with respect to 100 parts by mass of the first polymer, the dispersibility of the tackifier in the resin can be maintained, and initial adhesive strength can be easily obtained.

Among the above, it is preferable to use an acrylic polymer or a polyester polymer from the viewpoint of adhesive properties.

In the embodiment of the present invention, the acrylic polymer used as the organic polymer compound in the second polymer may be a commercially available polymer or may be obtained by polymerizing an acrylic monomer component.

Commercially available acrylic polymers used as the organic polymer compound in the second polymer include, for example, ARUFON UH2170 and UC3000 (manufactured by Toa Synthetics Co., Ltd.).

As the acrylic monomer component, any acrylic monomer can be used, and examples include hydroxyl-containing acrylic monomers and polymerizable acrylic monomers.

The acrylic monomer component constituting the organic polymer compound in the second polymer preferably contains a polymerizable acrylic monomer. The number of polymerizable acrylic monomers contained in the acrylic monomer component may be one, or two or more types may be used.

Polymerizable monomers include, for example, acrylic acid (AA), N-vinyl-2-pyrrolidone, dicyclopentanyl methacrylate, methyl acrylate (MA), methyl methacrylate (MMA), and cyclohexyl acrylic. Latex, cyclohexyl methacrylate (CHMA), isobornyl acrylate (IBXMA), β-carboxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, acrylonitrile, acrylamide, dimethyl acrylamide , isopropylacrylamide, hydroxyethylacrylamide, hydroxymethylacrylamide, hydroxybutylacrylamide, acryloylmorpholine (ACMO), 1-vinylimidazole, etc., and the effect of the present invention Since it can be expressed more, acrylic acid, methyl acrylate (MA), methyl methacrylate (MMA), cyclohexyl acrylate, cyclohexyl methacrylate (CHMA), and isobornyl acrylate (IBXMA) are preferred. and acryloylmorpholine (ACMO), more preferably acrylic acid (AA), cyclohexyl acrylate, cyclohexyl methacrylate (CHMA), and isobornyl acrylate (IBXMA). At least one species is selected.

The content ratio of the polymerizable monomer in the acrylic monomer component is preferably 1% by mass or more, more preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more from the viewpoint of adhesive properties. And, it is particularly preferable that it is 80% by mass or more.

Specific examples of hydroxyl group-containing monomers include 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate (4HBA), and 4-hydroxy. Roxybutyl methacrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate Hydroxyalkyl (meth)acrylates such as; Hydroxyalkylcycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate; Other hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether; etc. can be mentioned.

As the hydroxyl group-containing monomer, hydroxyalkyl (meth)acrylate is preferable among these, from the viewpoint of ease of handling and the ability to further express the effects of the present invention, and hydroxyalkyl (meth)acrylate having a hydroxyalkyl group having 2 to 6 carbon atoms. Alkyl (meth)acrylate is more preferable, and specifically, it is preferably at least one selected from 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, and more preferably is 4-hydroxybutylacrylate (4HBA).

The content ratio of the hydroxyl group-containing monomer in the acrylic monomer component is preferably 1% by mass or more, more preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more from the viewpoint of adhesive properties. And, it is particularly preferable that it is 15% by mass or more. Moreover, from the viewpoint of adhesive properties, it is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

The organic polymer compound in the second polymer according to the embodiment of the present invention can be produced by any appropriate polymerization within the range that does not impair the effect of the present invention.

Methods for polymerizing the organic polymer compound in the second polymer according to the embodiment of the present invention include, for example, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method using active energy ray irradiation (activated energy pre-polymerization method), and the like. Among these, the bulk polymerization method and the solution polymerization method are preferable, and the solution polymerization method is more preferable.

Solvents that can be used in polymerization include, for example, esters such as ethyl acetate and n-butyl acetate; Aromatic hydrocarbons such as toluene and benzene; Aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; Ketones such as methyl ethyl ketone and methyl isobutyl ketone; Organic solvents such as these can be mentioned. There may be only one type of solvent, and two or more types may be used.

In polymerization, any appropriate polymerization initiator (for example, a thermal polymerization initiator, a photo polymerization initiator, etc.) can be employed as long as it does not impair the effect of the present invention. The number of polymerization initiators may be one, or two or more types may be used. Additionally, when carrying out solution polymerization, it is preferable to use an oil-soluble polymerization initiator.

As the thermal polymerization initiator, any appropriate thermal polymerization initiator can be employed as long as it does not impair the effects of the present invention. The number of thermal polymerization initiators may be one, or two or more types may be used. Examples of thermal polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile (AMBN), and 2,2'-azobis. (2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovalerian acid, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2' -Azobis(2,4-dimethylvaleronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), etc. Azo-based initiator; Benzoyl peroxide, t-butylhydroperoxide, di-t-butyl peroxide, t-butylperoxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5- and peroxide-based initiators such as trimethylcyclohexane and 1,1-bis(t-butylperoxy)cyclododecane.

The amount of the thermal polymerization initiator used is, for example, preferably 0.1 to 15 parts by mass, based on 100 parts by mass of all monomers (monomer composition) that can be used to form the organic polymer compound in the second polymer. am.

As the photopolymerization initiator, any appropriate photopolymerization initiator can be employed as long as it does not impair the effects of the present invention. The number of photopolymerization initiators may be one, or two or more types may be used. Such photopolymerization initiators include, for example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, and photoactive oxime-based photopolymerization. Examples include initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.

The amount of the photopolymerization initiator used is, for example, preferably 0.001 to 0.5 parts by mass, based on 100 parts by mass of all monomers (monomer composition) that can be used to form the organic polymer compound in the second polymer. am.

When polymerizing the organic polymer compound in the second polymer, a chain transfer agent may be used to adjust the molecular weight. Chain transfer agents include, for example, 2-mercaptoethanol, α-thioglycerol, 2,3-dimercapto-1-propanol, octylmercaptan, t-nonylmercaptan, and dodecylmercaptan (laurylmercaptan). captan), t-dodecyl mercaptan, glycidyl mercaptan, thioglycolic acid, methyl thioglycolic acid, ethyl thioglycolic acid, propyl thioglycolic acid, butyl thioglycolic acid, t-butyl thioglycolic acid, thioglycolic acid 2-ethylhexyl, octyl thioglycolic acid, isooctyl thioglycolic acid, decyl thioglycolic acid, dodecyl thioglycolic acid, thioglycolic acid ester of ethylene glycol, thioglycolic acid ester of neopentyl glycol, thioglycolic acid of pentaerythritol. Ester, α-methylstyrene dimer, etc. are mentioned. Among these, from the viewpoint of suppressing whitening of the double-sided adhesive tape of the present invention, 2-mercaptoethanol and methyl thioglycolate are preferable, and 2-mercaptoethanol is especially preferable. There may be only one type of chain transfer agent, or two or more types may be used.

The amount of the chain transfer agent used is, for example, preferably 0.1 to 20 parts by mass, based on 100 parts by mass of all monomers (monomer composition) that can be used to form the organic polymer compound in the second polymer, More preferably, it is 0.2 parts by mass to 15 parts by mass, and even more preferably, it is 0.3 parts by mass to 10 parts by mass.

The weight average molecular weight of the organic polymer compound in the second polymer is not particularly limited, but is preferably 5 million or more and 1 million or less. The upper limit of the weight average molecular weight is more preferably 800,000, still more preferably 600,000, even more preferably 400,000, even more preferably 200,000, even more preferably 100,000, even more preferably 10,000. , the lower limit is more preferably 1000, still more preferably 2000, even more preferably 3000, and still more preferably 4000. If the weight average molecular weight is 500 or more, the problem of contamination of the surface of the adherend after peeling off the adhesive layer due to surface segregation can be effectively suppressed. Moreover, if the weight average molecular weight is 1 million or less, the problem that the cohesion of the adhesive layer decreases and glue remains on the adherend after peeling can be effectively suppressed.

The second polymer can be used individually or in combination of two or more types.

In the adhesive composition according to the embodiment of the present invention, the content of the organic polymer compound in the second polymer is from the viewpoint of adhesive properties with respect to 100 parts by mass of the first polymer or 100 parts by mass of the monomer mixture that is the raw material of the first polymer. It is preferably 1 part by mass or more, more preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and more preferably 25 parts by mass or more. It is more preferable, and it is even more preferable that it is 30 parts by mass or more. Moreover, from the viewpoint of adhesive properties, it is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, even more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less.

The content of the organic polymer compound in the second polymer may be 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer.

These second polymers may be added after obtaining the first polymer, or may be blended with the monomer mixture that is the raw material for the first polymer and undergo a polymerization reaction before obtaining the first polymer. However, the first polymer and the second polymer are It is preferable to combine them after each polymerization reaction.

In the pressure-sensitive adhesive composition according to the embodiment of the present invention, it is preferable that the HSP value difference between the first polymer and the second polymer is 0 to 3, and the HSP value difference of the organic polymer compound in the first polymer and the second polymer is 0 to 3. It is more preferable that it is 3.

The HSP value difference (ΔHSP value) between the first polymer and the second polymer is the difference between the HSP value of the first polymer and the HSP value of the second polymer.

When the HSP value difference is small, the compatibility between the first polymer and the second polymer tends to be good, and when the HSP value difference is large, the compatibility between the first polymer and the second polymer tends to be poor. From the viewpoint of compatibility, the HSP value difference between the first polymer and the second polymer is preferably 3 or less, more preferably 2.5 or less, and even more preferably 2 or less.

Here, the Hansen solubility parameter (HSP value) is the physical property value of a substance, including the dispersion term (δD), which is the energy derived from the dispersion force between molecules, the polarization term (δP), which is the energy derived from the polar force between molecules, and the hydrogen between molecules. It is expressed in terms of hydrogen bonding term (δH), which is energy derived from bonding force, and it is known that substances with similar HSP values exhibit physical properties that are close to each other.

The HSP value may be a known value or may be calculated using personal computer software HSPiP (source: http://www.hansen-solubility.com/index.html).

In the pressure-sensitive adhesive composition according to the embodiment of the present invention, the difference in HSP value between the first polymer and the second polymer can be adjusted by the type, compounding amount, etc. of the first polymer and the second polymer used.

(ionic liquid)

The ionic liquid in the embodiment of the present invention is not particularly limited as long as it is a molten salt (room temperature molten salt) that is composed of a pair of anions and cations and is liquid at 25°C. Examples of anions and cations are given below. Among the ionic substances obtained by combining them, those that are liquid at 25°C are ionic liquids, and those that are solid at 25°C are not ionic liquids but ionic solids described later.

Anions of ionic liquids are, for example, (FSO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₂ N ^- , (CF ₃ CF ₂ SO ₂ ) ₂ N ^- , (CF ₃ SO ₂ ) ₃ C ^- , Br ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , NO ₃ ^- , BF ₄ ^- , PF ₆ ^- , CH ₃ COO ^- , CF ₃ COO ^- , CF ₃ CF ₂ CF ₂ COO ^- , CF ₃ SO ₃ ^- , CF ₃ (CF ₂ ) ₃ SO ₃ ^- , AsF ₆ ^- , SbF ₆ ^- , and F(HF) _n ^- . Among them, anions include (FSO ₂ ) ₂ N ^- [bis (fluorosulfonyl) imide anion], and (CF ₃ SO ₂ ) ₂ N ^- [bis (trifluoromethanesulfonyl) imide. Anions of sulfonylimide-based compounds such as [anions] are preferable because they are chemically stable and provide good electrical peelability. That is, the anion of the ionic liquid preferably contains at least one selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion. .

Cations in the ionic liquid are preferably nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium cations because they are chemically stable and provide good electrical separation properties, and are imidazolium-based and ammonium. Systemic, pyrrolidinium-based, and pyridinium-based cations are more preferred.

Examples of imidazolium-based cations include 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, and 1-butyl. -3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-heptyl-3-methylimidazolium cation, 1 -Octyl-3-methylimidazolium cation, 1-nonyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium Cation, 1-tridecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation, 1-pentadecyl-3-methylimidazolium cation, 1-hexadecyl- 3-methylimidazolium cation, 1-heptadecyl-3-methylimidazolium cation, 1-octadecyl-3-methylimidazolium cation, 1-undecyl-3-methylimidazolium cation , 1-benzyl-3-methylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, and 1,3-bis(dodecyl)imidazolium cation.

Examples of pyridinium-based cations include 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, and 1-butyl-4-methylpyridinium. cation, and 1-octyl-4-methylpyridinium cation.

Examples of pyrrolidinium-based cations include 1-ethyl-1-methylpyrrolidinium cation and 1-butyl-1-methylpyrrolidinium cation.

Ammonium-based cations include, for example, tetraethylammonium cation, tetrabutylammonium cation, methyltrioctylammonium cation, tetradecyltrihexylammonium cation, glycidyltrimethylammonium cation, and trimethylaminoethylacryl. Late cation, etc. can be mentioned.

As an ionic liquid, from the viewpoint of increasing the rate of decrease in adhesive strength when voltage is applied, it is preferable to select a cation with a molecular weight of 160 or less as a constituting cation, and the (FSO ₂ ) ₂ N ^- [bis (fluo) above rosulfonyl)imide anion] or (CF ₃ SO ₂ ) ₂ N ^- [bis(trifluoromethanesulfonyl)imide anion] and an ionic liquid containing a cation with a molecular weight of 160 or less are particularly preferred. . Cations with a molecular weight of 160 or less include, for example, 1-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-propyl-3-methylimidazolium cation, 1- Butyl-3-methylimidazolium cation, 1-pentyl-3-methylimidazolium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium Cation, 1-butyl-4-methylpyridinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-butyl-1-methylpyrrolidinium cation, tetraethylammonium cation, glycidyl Trimethylammonium cation, trimethylaminoethyl acrylate cation, etc. are mentioned.

Moreover, as the cation of the ionic liquid, cations represented by the following formulas (2-A) to (2-D) are also preferable.

[Formula 1]

R ¹ in formula (2-A) represents a hydrocarbon group with 4 to 10 carbon atoms (preferably a hydrocarbon group with 4 to 8 carbon atoms, more preferably a hydrocarbon group with 4 to 6 carbon atoms), and may contain a hetero atom. R ² and R ³ are the same or different and are a hydrogen atom or a hydrocarbon group with 1 to 12 carbon atoms (preferably a hydrocarbon group with 1 to 8 carbon atoms, more preferably a hydrocarbon group with 2 to 6 carbon atoms, even more preferably In other words, it represents a hydrocarbon group having 2 to 4 carbon atoms) and may also contain a hetero atom. However, when a nitrogen atom forms a double bond with an adjacent carbon atom, R ³ does not exist.

R ⁴ in formula (2-B) represents a hydrocarbon group with 2 to 10 carbon atoms (preferably a hydrocarbon group with 2 to 8 carbon atoms, more preferably a hydrocarbon group with 2 to 6 carbon atoms), and may contain a hetero atom. and R ⁵ , R ⁶ , and R ⁷ are the same or different and are a hydrogen atom or a hydrocarbon group with 1 to 12 carbon atoms (preferably a hydrocarbon group with 1 to 8 carbon atoms, more preferably a hydrocarbon group with 2 to 6 carbon atoms) group, more preferably a hydrocarbon group having 2 to 4 carbon atoms), and may also contain a hetero atom.

R ⁸ in formula (2-C) represents a hydrocarbon group with 2 to 10 carbon atoms (preferably a hydrocarbon group with 2 to 8 carbon atoms, more preferably a hydrocarbon group with 2 to 6 carbon atoms), and may contain a hetero atom. and R ⁹ , R ¹⁰ , and R ¹¹ are the same or different, and are a hydrogen atom or a hydrocarbon group with 1 to 16 carbon atoms (preferably a hydrocarbon group with 1 to 10 carbon atoms, more preferably a hydrocarbon group with 1 to 8 carbon atoms) group) and may contain a hetero atom.

In formula ⁽ 2 ^{- D} ) ^, represents a hydrocarbon group with 1 to 14 carbon atoms, more preferably a hydrocarbon group with 1 to 10 carbon atoms, even more preferably a hydrocarbon group with 1 to 8 carbon atoms, particularly preferably a hydrocarbon group with 1 to 6 carbon atoms), and a hetero atom You may include it. However, when X is a sulfur atom, R ¹² does not exist.

In an embodiment of the present invention, the cation of the ionic liquid preferably contains at least one selected from the group consisting of a nitrogen-containing onium cation, a sulfur-containing onium cation, and a phosphorus-containing onium cation.

The molecular weight of the cation in the ionic liquid is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, further preferably 250 or less, particularly preferably 200 or less, most preferably 160 or less. am. Also, it is usually 50 or more. It is thought that cations in the ionic liquid have the property of moving toward the cathode in the adhesive layer when voltage is applied and being biased toward the vicinity of the interface between the adhesive layer and the adherend. In the present invention, for this reason, the adhesive strength during voltage application decreases relative to the initial adhesive strength, and electrical peeling occurs. A cation with a small molecular weight, such as 500 or less, is preferable because it facilitates the movement of the cation to the cathode side in the pressure-sensitive adhesive layer and increases the rate of decrease in adhesive strength when voltage is applied.

Commercially available ionic liquids include, for example, "Elexel AS-110", "Elexel MP-442", "Elexel IL-210", and "Elexel MP-471" manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd. Examples include “Elexel MP-456,” “Elexel AS-804,” “HMI-FSI” manufactured by Mitsubishi Materials Co., Ltd., “CIL-312” and “CIL-313” manufactured by Nippon Kalit Co., Ltd.

The ionic conductivity of the ionic liquid is preferably 0.1 mS/cm or more. More preferably 1 mS/cm or more, further preferably 3 mS/cm or more, even more preferably 5 mS/cm or more, even more preferably 10 mS/cm or more, particularly preferably 15 mS/cm or more. It is mS/cm or more, and most preferably it is 20 mS/cm or more. There is no particular upper limit, but by having the above ionic conductivity, the adhesive strength is sufficiently reduced even at a low voltage. In addition, ion conductivity can be measured by the AC impedance method, for example, using a 1260 frequency response analyzer manufactured by Solartron.

The content (compounding amount) of the ionic liquid in the adhesive composition according to the embodiment of the present invention is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the first polymer from the viewpoint of reducing the adhesive force during voltage application, and is 30 parts by mass. The values below are preferable from the viewpoint of increasing initial adhesion. From the same viewpoint, it is more preferable that it is 20 parts by mass or less, even more preferably 15 parts by mass or less, especially preferably 10 parts by mass or less, and most preferably 5 parts by mass or less. Moreover, it is more preferable that it is 0.6 parts by mass or more, it is still more preferable that it is 0.8 parts by mass or more, it is especially preferable that it is 1.0 parts by mass or more, and it is most preferable that it is 1.5 parts by mass or more.

(Other ingredients)

The pressure-sensitive adhesive composition according to the embodiment of the present invention may contain one or more components other than the polymer and the ionic liquid (hereinafter sometimes referred to as “other components”), if necessary, to the extent that they do not impair the effect of the present invention. It may contain two or more types. Hereinafter, other components that may be contained in the pressure-sensitive adhesive composition according to the embodiment of the present invention will be described.

The adhesive composition according to the embodiment of the present invention may contain an ionic additive for the purpose of controlling the electrical peeling force. As an ionic additive, for example, an ionic solid can be used.

Ionic solids are ionic substances that are solid at 25°C. The ionic solid is not particularly limited, but for example, among the ionic substances obtained by combining the anion and cation illustrated in the description of the ionic liquid described above, a solid one can be used. When the adhesive composition contains an ionic solid, the content of the ionic solid is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and 10 parts by mass or less with respect to 100 parts by mass of the first polymer. is preferable, 5 parts by mass or less is more preferable, and 2.5 parts by mass or less is still more preferable.

The adhesive composition according to the embodiment of the present invention may contain a crosslinking agent as needed for the purpose of improving creep properties and shear properties by crosslinking the polymer. Crosslinking agents include, for example, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, oxazoline-based crosslinking agents, and aziridine-based crosslinking agents. Crosslinking agents, amine-based crosslinking agents, etc. can be mentioned. Examples of the isocyanate-based crosslinking agent include toluene diisocyanate and methylene bisphenyl isocyanate. Epoxy-based crosslinking agents include, for example, N,N,N',N'-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis (N,N-diglycy Dilaminomethyl) cyclohexane and 1,6-hexanediol diglycidyl ether can be mentioned. When containing a crosslinking agent, the content is preferably 0.1 parts by mass or more, more preferably 0.7 parts by mass or more, preferably 50 parts by mass or less, and 10 parts by mass or less with respect to 100 parts by mass of the first polymer. It is more preferable, and 3 parts by mass or less is still more preferable. In addition, the crosslinking agent can be used individually or in combination of two or more types.

The adhesive composition according to the embodiment of the present invention may contain polyethylene glycol or tetraethylene glycol dimethyl ether as needed for the purpose of assisting the movement of the ionic liquid when voltage is applied. As polyethylene glycol or tetraethylene glycol dimethyl ether, those having a number average molecular weight of 100 to 6000 can be used. When these components are contained, the content is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, still more preferably 1 part by mass or more, and also 30 parts by mass, relative to 100 parts by mass of the first polymer. The following is preferable, 20 mass parts or less is more preferable, and 15 mass parts or less is still more preferable.

The adhesive composition according to the embodiment of the present invention may contain a conductive filler as needed for the purpose of imparting conductivity to the adhesive composition. The conductive filler is not particularly limited, and generally known or common conductive fillers can be used. For example, graphite, carbon black, carbon fiber, metal powder such as silver or copper, etc. can be used. The content when containing the conductive filler is preferably 0.1 part by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the first polymer.

The adhesive composition according to the embodiment of the present invention may contain a corrosion inhibitor as needed for the purpose of suppressing corrosion of the metal adherend. The corrosion inhibitor is not particularly limited, and generally known or common corrosion inhibitors can be used. For example, carbodiimide compounds, adsorption-type inhibitors, chelate-forming metal deactivators, etc. can be used.

Carbodiimide compounds include, for example, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N,N '-Dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, N-cyclohexyl-N'-(2-morpholinoethyl) Carbodiimide, N,N'-di-tert-butylcarbodiimide, 1,3-bis(p-tolyl)carbodiimide, and polycarbodiimide resins using these as monomers. These carbodiimide compounds can be used individually or in combination of two or more types. When the pressure-sensitive adhesive composition according to the embodiment of the present invention contains the carbodiimide compound, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the first polymer.

Examples of adsorption-type inhibitors include alkylamines, carboxylic acid salts, carboxylic acid derivatives, and alkyl phosphates. Adsorption-type inhibitors can be used individually or in combination of two or more types. When the pressure-sensitive adhesive composition according to the embodiment of the present invention contains an alkylamine as an adsorption-type inhibitor, the content is preferably 0.01 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the first polymer. When the pressure-sensitive adhesive composition according to the embodiment of the present invention contains a carboxylate as an adsorption-type inhibitor, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the first polymer. When the pressure-sensitive adhesive composition according to the embodiment of the present invention contains a carboxylic acid derivative as an adsorption-type inhibitor, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the first polymer. When the pressure-sensitive adhesive composition according to the embodiment of the present invention contains an alkyl phosphate as an adsorption-type inhibitor, the content is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the first polymer.

As a chelate-forming metal deactivator, for example, a triazole group-containing compound or a benzotriazole group-containing compound can be used. These are preferable because they have a high effect of deactivating the surface of metals such as stainless steel and aluminum, and they do not affect adhesiveness easily even if they are included in the adhesive component. Chelate-forming metal deactivators can be used individually or in combination of two or more types. When the adhesive composition according to the embodiment of the present invention contains the chelate-forming metal deactivator, the content is preferably 0.01 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the first polymer.

The total content (compounding amount) of the corrosion inhibitor is preferably 0.01 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the first polymer.

The adhesive composition according to the embodiment of the present invention further contains various additives such as fillers, plasticizers, anti-aging agents, antioxidants, pigments (dyes), flame retardants, solvents, surfactants (leveling agents), rust inhibitors, and antistatic agents. You can do it. The total content of these components is not particularly limited as long as the effect of the present invention is achieved, but is preferably 0.01 parts by mass or more and 20 parts by mass or less, more preferably 10 parts by mass, relative to 100 parts by mass of the first polymer. or less, more preferably 5 parts by mass or less.

Examples of fillers include silica, iron oxide, zinc oxide, aluminum oxide, titanium oxide, barium oxide, magnesium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, pyrophyllite clay, kaolin clay, and calcined clay. .

The plasticizer can be a known plasticizer used in general resin compositions, etc., for example, oils such as paraffin oil and process oil, liquid polyisoprene, liquid polybutadiene, liquid rubber such as liquid ethylene-propylene rubber, and tetramethylene. Hydrophthalic acid, azelaic acid, benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, citric acid, and their derivatives, dioctylphthalate (DOP), dibutyl Phthalate (DBP), dioctyl adipate, diisononyl adipate (DINA), and isodecyl succinate can be used.

Anti-aging agents include, for example, hindered phenol-based compounds, aliphatic and aromatic hindered amine-based compounds, and the like.

Antioxidants include, for example, butylhydroxytoluene (BHT) and butylhydroxyanisole (BHA).

Pigments include, for example, inorganic pigments such as titanium dioxide, zinc oxide, ultramarine, bengala, lithopone, lead, cadmium, iron, cobalt, aluminum, hydrochloride, and sulfate, organic pigments such as azo pigments, and copper phthalocyanine pigments. etc. can be mentioned.

Examples of rust preventive agents include zinc phosphate, tannic acid derivatives, phosphoric acid esters, basic sulfonates, and various rust preventive pigments.

Examples of adhesion-imparting agents include titanium coupling agents and zirconium coupling agents.

Antistatic agents generally include quaternary ammonium salts or hydrophilic compounds such as polyglycolic acid or ethylene oxide derivatives.

＜Initial adhesion, rate of decline in adhesion due to voltage application＞

The adhesive strength of the adhesive composition according to the embodiment of the present invention can be evaluated by various methods, for example, by the 180° peel test described in the Examples column.

The adhesive composition according to the embodiment of the present invention preferably has an initial adhesive force of 1.5 N/cm or more, as measured by forming an adhesive sheet as described in the Examples column and performing a 180° peel test, and is 2.0 N/cm or more. It is more preferable, it is more preferable that it is 2.5 N/cm or more, it is especially preferable that it is 3.0 N/cm or more, and it is most preferable that it is 3.5 N/cm or more. If the initial adhesive force is 1.5 N/cm or more, adhesion to the adherend is sufficient, and it is difficult for the adherend to peel or shift.

In addition, the adhesive composition according to the embodiment of the present invention forms an adhesive sheet as described in the Examples column, leaves it in an environment of a predetermined temperature and humidity for a predetermined period, and applies a voltage of 30 V for 30 seconds. It is desirable that the adhesive force measured by the 180° peel test while applying a voltage of 30 V is sufficiently small relative to the initial adhesive force.

That is, it is preferable that the adhesive force measured by the above method (in the formula (C) below, simply expressed as "adhesion force during voltage application") and the adhesive force decline rate calculated from the initial adhesive force by the formula (C) below are 75% or more. and is preferably 80% or more. The predetermined temperature, humidity and period are preferably 60°C 90% RH for 168 hours, and particularly preferably 60°C 90% RH 500 hours. If the adhesive strength after lapse of 60°C, 90% RH, 500 hours is sufficiently small relative to the initial adhesive strength, the wet heat stability is excellent even after storage in a high temperature, high humidity environment.

Adhesion decline rate (%) = {1 - (adhesion during voltage application/initial adhesion)} × 100 (C)

In addition, the applied voltage and voltage application time during electrical peeling are not limited to the above, and are not particularly limited as long as peeling of the adhesive sheet is possible. These preferred ranges are shown below.

The applied voltage is preferably 1 V or more, more preferably 3 V or more, and even more preferably 6 V or more. Moreover, it is preferable that it is 100 V or less, more preferably 50 V or less, even more preferably 30 V or less, and especially preferably 15 V or less.

The voltage application time is preferably 60 seconds or less, more preferably 40 seconds or less, further preferably 20 seconds or less, and especially preferably 10 seconds or less. In this case, workability is excellent. Also, the shorter the application time, the better, but it is usually 1 second or more.

<Method for producing adhesive composition>

The adhesive composition of the present invention is not particularly limited, but can be produced by appropriately stirring and mixing the polymer, ionic liquid, additives, and, if necessary, a crosslinking agent, polyethylene glycol, and conductive filler.

[Adhesive sheet]

(Composition of adhesive sheet)

The adhesive sheet according to the embodiment of the present invention is not particularly limited as long as it has at least one adhesive layer (hereinafter also referred to as “electrically peelable adhesive layer”) formed from the adhesive composition according to the embodiment of the present invention described above. . The pressure-sensitive adhesive sheet according to the embodiment of the present invention may have a pressure-sensitive adhesive layer (hereinafter sometimes referred to as “other pressure-sensitive adhesive layer”) that does not contain an ionic liquid other than the electrically peelable pressure-sensitive adhesive layer. The adhesive sheet according to the embodiment of the present invention may have a base material, a conductive layer, a base material for electricity conduction, an intermediate layer, an undercoat layer, etc. in addition to the above. The adhesive sheet according to the embodiment of the present invention may be, for example, wound into a roll or a sheet. In addition, “adhesive sheet” shall also include the meaning of “adhesive tape”. That is, the adhesive sheet according to the embodiment of the present invention may be an adhesive tape having a tape-like form.

The adhesive sheet according to the embodiment of the present invention may be a (substrate-less) double-sided adhesive sheet that does not have a base material and consists only of an electrically peelable adhesive layer, that is, does not contain a base layer. The adhesive sheet according to the embodiment of the present invention may be a double-sided adhesive sheet that has a base material and both sides of the base material are adhesive layers (electrically peelable adhesive layers or other adhesive layers). In addition, the pressure-sensitive adhesive sheet according to the embodiment of the present invention may be a single-sided pressure-sensitive adhesive sheet that has a substrate and only one side of the substrate is an adhesive layer (electrically peelable adhesive layer or other adhesive layer). In addition, the adhesive sheet according to the embodiment of the present invention may have a release liner for the purpose of protecting the adhesive layer surface, but the release liner is not included in the adhesive sheet according to the embodiment of the present invention.

The structure of the adhesive sheet according to the embodiment of the present invention is not particularly limited, but includes the adhesive sheet (X1) shown in FIG. 1, the adhesive sheet (X2) with a laminated structure shown in FIG. 2, and the adhesive sheet (X2) shown with a laminated structure in FIG. 3. Sheet (X3) is preferably used. The adhesive sheet (X1) is a base material-less double-sided adhesive sheet consisting only of the electrically peelable adhesive layer (1). The adhesive sheet (X2) is a double-sided adhesive formed with a substrate having a layer structure of an adhesive layer (2), an electrically conductive substrate (5) (substrate (3) and conductive layer (4)), and an electrically peelable adhesive layer (1). It's a sheet. The pressure-sensitive adhesive sheet ( It is a double-sided adhesive sheet formed with a base material having a layer structure of 3), a conductive layer (4)), and an adhesive layer (2). In the base material 5 for electrical conduction of the adhesive sheets (X2 and Moreover, in the adhesive sheet (X2) of FIG. 2, it may be a single-sided adhesive sheet without forming the adhesive layer (2).

The substrate (3) is not particularly limited, but includes paper-based substrates such as paper, fiber-based substrates such as cloth and non-woven fabric, various plastics (polyolefin-based resins such as polyethylene and polypropylene, polyester-based resins such as polyethylene terephthalate, Examples include plastic-based substrates such as films and sheets made of acrylic resins such as polymethyl methacrylate, and laminates thereof. The base material may have a single-layer form or a multi-layer form. Additionally, the substrate may be subjected to various treatments, such as backside treatment, antistatic treatment, and undercoat treatment, as necessary.

The conductive layer 4 is not particularly limited as long as it is a conductive layer, but may include metal (e.g., aluminum, magnesium, copper, iron, tin, gold, etc.) foil, metal plate (e.g., aluminum, magnesium, copper, etc.) , iron, tin, silver, etc.), a conductive polymer, etc. may be used, or a metal vapor deposition film formed on the base material 3 may be used.

The base material 5 for conducting electricity is not particularly limited as long as it is a base material having a conductive layer (conducting electricity), but examples include those in which a metal layer is formed on the surface of the base material, for example, the surface of the base material exemplified above. Examples include those in which the metal layer was formed by methods such as plating, chemical vapor deposition, and sputtering. Examples of the metal layer include the metals, metal plates, and conductive polymers exemplified above.

In the adhesive sheet (X1), it is preferable that the adherend on both sides is an adherend having a metal adherend. In the adhesive sheet (X2), it is preferable that the adherend on the side of the electrically peelable adhesive layer (1) is an adherend that has a metal adherend surface.

The metal adhesion surface includes a surface made of a metal having conductivity, for example, aluminum, copper, iron, magnesium, tin, gold, silver, and lead, etc., among which iron or aluminum. A surface made of metal (for example, stainless steel, etc.) is preferable. Examples of the adherend having a metal adhesion surface include sheets, parts, and plates made of metal containing aluminum, copper, iron, magnesium, tin, gold, silver, and lead as main components. The adherend other than the adherend having the metal adhered surface is not particularly limited, and includes fiber sheets such as paper, cloth, and non-woven fabric, and films and sheets of various plastics.

The thickness of the electrically peelable adhesive layer 1 is preferably 1 μm or more and 1000 μm or less from the viewpoint of initial adhesive strength. The upper limit of the thickness of the electrically peelable adhesive layer 1 is more preferably 500 μm, still more preferably 300 μm, even more preferably 200 μm, still more preferably 150 μm, and even more preferably It is 100 ㎛, more preferably 80 ㎛, more preferably 70 ㎛, even more preferably 60 ㎛, even more preferably 50 ㎛, the lower limit is more preferably 5 ㎛, even more preferably is 10 ㎛, more preferably 20 ㎛, and even more preferably 30 ㎛.

The thickness of the electrically peelable adhesive sheet of this embodiment is preferably 20 µm or more and 3000 µm or less. The upper limit of the thickness is more preferably 1000 ㎛, more preferably 500 ㎛, even more preferably 300 ㎛, even more preferably 250 ㎛, even more preferably 200 ㎛, even more preferably 150 ㎛. ㎛, more preferably 100 ㎛, and the lower limit is more preferably 30 ㎛, even more preferably 50 ㎛.

The thickness of the adhesive layer 2 is preferably 1 μm or more and 2000 μm or less from the viewpoint of adhesive strength. The upper limit of the thickness of the adhesive layer 2 is more preferably 1000 μm, further preferably 500 μm, particularly preferably 100 μm, and the lower limit is more preferably 3 μm, and still more preferably It is 5 ㎛, especially preferably 8 ㎛.

The thickness of the base material 3 is preferably 10 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500 μm, further preferably 300 μm, particularly preferably 100 μm, and the lower limit is more preferably 12 μm, and even more preferably 25 μm.

The thickness of the conductive layer 4 is preferably 0.001 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500 ㎛, more preferably 300 ㎛, even more preferably 50 ㎛, even more preferably 10 ㎛, and the lower limit is more preferably 0.01 ㎛, even more preferably Preferably it is 0.03 ㎛, more preferably 0.05 ㎛.

The thickness of the base material 5 for conducting electricity is preferably 10 μm or more and 1000 μm or less. The upper limit of the thickness is more preferably 500 μm, further preferably 300 μm, particularly preferably 100 μm, and the lower limit is more preferably 12 μm, and even more preferably 25 μm.

The surface of the electrically peelable adhesive layer and other adhesive layers of the adhesive sheet according to the embodiment of the present invention may be protected by a release liner. The release liner is not particularly limited, but includes a release liner in which the surface of a base material (liner base material) such as paper or plastic film is treated with silicone, and a release liner in which the surface of a base material (liner base material) such as paper or plastic film is laminated with a polyolefin resin. A peelable liner, etc. can be mentioned. The thickness of the release liner is not particularly limited, but is preferably 10 μm or more and 100 μm or less.

The thickness of the adhesive sheet according to the embodiment of the present invention is preferably 20 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 ㎛, more preferably 500 ㎛, even more preferably 300 ㎛, even more preferably 250 ㎛, even more preferably 200 ㎛, even more preferably 150 ㎛. ㎛, more preferably 100 ㎛, and the lower limit is more preferably 30 ㎛, even more preferably 50 ㎛.

In particular, in the case of the adhesive sheet (X2) shown in FIG. 2, the thickness of the adhesive sheet is preferably 50 μm or more and 2000 μm or less. The upper limit of the thickness is more preferably 1000 ㎛, more preferably 500 ㎛, even more preferably 300 ㎛, even more preferably 250 ㎛, even more preferably 200 ㎛, even more preferably 150 ㎛. ㎛, and the lower limit is more preferably 80 ㎛, and still more preferably 100 ㎛.

In particular, in the case of the adhesive sheet (X3) shown in FIG. 3, the thickness of the adhesive sheet is preferably 20 μm or more and 3000 μm or less. The upper limit of the thickness is more preferably 1000 ㎛, more preferably 500 ㎛, even more preferably 300 ㎛, even more preferably 250 ㎛, even more preferably 200 ㎛, even more preferably 150 ㎛. ㎛, and the lower limit is more preferably 50 ㎛, further preferably 80 ㎛, and still more preferably 100 ㎛.

The pressure-sensitive adhesive sheet according to the embodiment of the present invention may further include a coating layer. The coat layer is preferably formed between the electrically peelable adhesive layer and the conductive layer.

The electrically peelable adhesive sheet of the present embodiment further includes a coating layer, which serves as a barrier to the ionic liquid contained in the electrically peelable adhesive layer from penetrating into the conductive layer when voltage is applied, thereby preventing the conductive layer from peeling off from the substrate. It has a preventive effect.

In addition, because the coat layer is in contact with the electrically peelable adhesive layer, the adhesion between the electrically peelable adhesive layer and the conductive layer is improved, and the electrically peelable adhesive layer is thermally cured when exposed to a high temperature environment. It has the effect of preventing the interfacial adhesion of hyperconductive materials (e.g., adherends, etc.) from decreasing and peeling off within the electrically peelable adhesive sheet.

The coat layer is a layer whose main component is resin or an inorganic material, and can be formed from a resin composition mainly composed of a resin component or a composition mainly composed of an inorganic material.

The coat layer contains at least one type of resin selected from polyester resin, acrylic resin, epoxy resin, and urethane resin, or at least one type of inorganic material selected from SiNx, SiOx, Al ₂ O ₃ , Ni, and NiCr. It is desirable.

(Method of manufacturing adhesive sheet)

The manufacturing method of the pressure-sensitive adhesive sheet according to the embodiment of the present invention can use known or customary manufacturing methods. The electrically peelable adhesive layer in the adhesive sheet according to the embodiment of the present invention is prepared by applying a solution in which the adhesive composition according to the embodiment of the present invention is dissolved in a solvent as needed, onto a release liner, and drying and/or A method of hardening, etc. can be mentioned. In addition, other adhesive layers include a method of applying a solution in which an adhesive composition containing no ionic liquid and no additives is dissolved in a solvent as needed on a release liner, followed by drying and/or curing. Additionally, the solvent and release liner can be those exemplified above.

At the time of application, a conventional coater (for example, a gravure roll coater, reverse roll coater, kiss roll coater, deep roll coater, bar coater, knife coater, spray roll coater, etc.) can be used.

By the above method, an electrically peelable adhesive layer and other adhesive layers can be manufactured, and the present invention can be obtained by appropriately laminating the electrically peelable adhesive layer and other adhesive layers on a base material, a conductive layer, and a conductive base material. The pressure-sensitive adhesive sheet according to the embodiment can be manufactured. In addition, instead of the release liner, an adhesive sheet may be manufactured by applying an adhesive composition using a base material, a conductive layer, and a current conductive base material.

(Method for electrical peeling of adhesive sheets)

Peeling of the adhesive sheet according to the embodiment of the present invention from the adherend can be performed by applying a voltage to the electrically peelable adhesive layer to generate a potential difference in the thickness direction of the electrically peelable adhesive layer.

For example, a bonded body in which the adhesive sheet (X1) is attached to a conductive adherend can be peeled off by passing electricity to the conductive adherend and applying a voltage to the electrically peelable adhesive layer.

When the electrically peelable adhesive layer side of the adhesive sheet ( .

In the case of the adhesive sheet (X3), it can be peeled by energizing the conductive layers (4) on both sides and applying a voltage to the electrically peelable adhesive layer.

Electricity is preferably applied by connecting terminals to one end of the adhesive sheet and the other end so that voltage is applied to the entire electrically peelable adhesive layer. In addition, when the adherend has a metal adherend, the one end and the other end may be a part of the adherend having the metal adherend. Additionally, at the time of peeling, voltage may be applied after adding water to the interface between the metal adhesion surface and the electrically peelable adhesive layer.

(Purpose of adhesive sheet)

Conventional re-release techniques include an adhesive layer that is peeled off by curing by ultraviolet (UV) irradiation or an adhesive layer that is peeled off by heat. A pressure-sensitive adhesive sheet using such a pressure-sensitive adhesive layer cannot be used in cases where ultraviolet (UV) irradiation is difficult or when heat causes damage to the member to be adhered. Since the adhesive sheet according to the embodiment of the present invention provided with the electrically peelable adhesive layer does not use ultraviolet rays or heat, it can be easily peeled by applying voltage without damaging the adherend member.

Due to the above characteristics, the adhesive sheet according to the embodiment of the present invention can be used as a secondary battery (for example, a lithium ion battery pack) used in mobile terminals such as smartphones, mobile phones, laptop computers, video cameras, and digital cameras. It is suitable for use in fixing the case body. Additionally, the adhesive sheet according to the embodiment of the present invention is suitable for use in fixing vehicle members (eg, batteries, motors, etc.). And, the adhesive sheet according to the embodiment of the present invention is suitable for fixation purposes (for example, ceramic capacitors, lithium ion batteries, etc.) in semiconductor manufacturing processes and inspections. Additionally, the adhesive sheet according to the embodiment of the present invention is suitable for protection purposes in a metal processing process (for example, stainless steel plates for railroads, etc.).

In addition, rigid members as objects of bonding with the adhesive sheet according to the embodiment of the present invention include, for example, silicon substrates for semiconductor wafers, sapphire substrates for LEDs, SiC substrates and metal base substrates, and TFTs for displays. Examples include substrates, color filter substrates, and base substrates for organic EL panels. Weak members that are subject to bonding with a double-sided adhesive sheet include, for example, semiconductor substrates such as compound semiconductor substrates, silicon substrates for MEMS devices, passive matrix substrates, surface cover glass for smartphones, and touch panels on the cover glass. Examples include OGS (One Glass Solution) substrates on which sensors are installed, organic substrates and organic-inorganic hybrid substrates mainly composed of silsesquioxane, flexible glass substrates for flexible displays, and graphene sheets.

[Conjugate]

A bonded body according to an embodiment of the present invention is a bonded body comprising the adhesive sheet according to the embodiment of the present invention and a conductive material, and the electrically peelable adhesive layer in the adhesive sheet is adhered to the conductive material.

The conductive material is preferably an adherend having a metal adhesion surface. Examples of the adherend having a metal adhesion surface include metals containing aluminum, copper, iron, magnesium, tin, gold, silver, and lead as main components. Among them, a metal containing aluminum is preferable.

As a bonded body of the present embodiment, for example, the adhesive sheet (X1) and the electrically peelable adhesive layer (1) side of the adhesive sheet ( A bonded conjugate, etc. can be mentioned.

Examples of the bonded body of the present embodiment include, for example, a bonded body and adhesive sheet in which the other adhesive layers 2 on both sides of the adhesive sheet Examples include a bonded body in which any other adhesive layer (2) in (X3) is bonded to a non-conductive material.

Examples of bonded bodies according to embodiments of the present invention include, for example, adhesive sheet (X1), which is provided with adherends having metal adhesion surfaces on both sides of the electrically peelable adhesive layer (1), and adhesive sheet (X2). As an adhesive sheet (X3), a bonded body provided with an adherend having a metal adhesion surface on the electrically peelable adhesive layer (1) side and an adherend on the adhesive layer (2) side, A bonded body provided with an adherend on both sides, etc. can be mentioned.

As described above, the following matters are disclosed in this specification.

＜1＞

An adhesive composition containing a first polymer and an ionic liquid,

Comprising the first polymer as a base polymer,

An adhesive composition further comprising a second polymer having a glass transition temperature (Tg) of 40 to 180°C.

＜2＞

The pressure-sensitive adhesive composition according to <1>, wherein the HSP value difference between the first polymer and the second polymer is 0 to 3.

＜3＞

In <1> or <2>, the second polymer contains an organic polymer compound, and the content of the organic polymer compound in the second polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer. The adhesive composition described.

＜4＞

The anion of the ionic liquid includes <1> at least one selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion. The adhesive composition according to any one of to <3>.

＜5＞

The cation of the ionic liquid is any one of <1> to <4>, including at least one member selected from the group consisting of nitrogen-containing onium cation, sulfur-containing onium cation, and phosphorus-containing onium cation. The adhesive composition described.

＜6＞

The adhesive composition according to any one of <1> to <5>, wherein the content of the ionic liquid is 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the first polymer.

＜7＞

The first polymer contains at least one member selected from the group consisting of a polyester polymer, a urethane polymer, and an acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond. The adhesive composition according to any one of <6>.

＜8＞

The adhesive composition according to any one of <1> to <7>, in which the second polymer contains a tackifier resin.

＜9＞

The adhesive composition according to <8>, wherein the softening point of the tackifying resin is 100°C or higher.

＜10＞

The adhesive composition according to <8> or <9>, wherein the content of the tackifying resin is 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer.

＜11＞

The adhesive composition according to any one of <8> to <10>, wherein the tackifying resin is a terpene-based tackifying resin or a rosin-based tackifying resin.

＜12＞

The adhesive composition according to any one of <1> to <11>, which is for electrical peeling.

＜13＞

An adhesive sheet comprising an adhesive layer formed from the adhesive composition according to any one of <1> to <12>.

＜14＞

<13> Equipped with the adhesive sheet described in and a conductive material,

A bonded body in which the adhesive layer is adhered to the conductive material.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. The following weight average molecular weight is measured by gel permeation chromatography (GPC) method.

＜First polymer＞

(Preparation of acrylic polymer 1 solution)

As monomer components, n-butylacrylate (BA): 87 parts by mass, 2-methoxyethyl acrylate (MEA): 10 parts by mass, acrylic acid (AA): 3 parts by mass, and as a polymerization solvent, ethyl acetate: 150 parts by mass. The mixture was placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 63°C, and reaction was carried out for 6 hours. After that, ethyl acetate was added to obtain an acrylic polymer 1 solution with a solid content concentration of 40 mass%. The weight average molecular weight of the obtained acrylic polymer 1 was 750,000. Additionally, Tg was -45°C.

(Preparation of acrylic polymer 2 solution)

As monomer components, n-butylacrylate (BA): 95 parts by mass, acrylic acid (AA): 5 parts by mass, and ethyl acetate: 150 parts by mass as a polymerization solvent were placed in a separable flask, and while introducing nitrogen gas, 1. It was stirred for some time. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 63°C, and reaction was carried out for 6 hours. After that, ethyl acetate was added to obtain an acrylic polymer 2 solution with a solid content concentration of 40 mass%. The weight average molecular weight of the obtained acrylic polymer 2 was 600,000. Additionally, Tg was -47°C.

＜Second polymer＞

(polymer 1)

As a monomer component, cyclohexyl methacrylate (CHMA): 95 parts by mass, acrylic acid (AA): 5 parts by mass, ethyl acetate: 300 parts by mass as a polymerization solvent, and 2-mercaptoethanol (thioglycol) as a chain transfer agent: 3 parts by mass were put into a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 65°C, and reaction was carried out for 3 hours, and then continued at 75°C. It was made to react for 2 hours, and the polymer 1 solution with a solid content concentration of 25 mass % was obtained.

(polymer 2)

Isobornyl methacrylate (IBXMA): 100 parts by mass as a monomer component, ethyl acetate: 300 parts by mass as a polymerization solvent, and 2-mercaptoethanol (thioglycol): 3 parts by mass as a chain transfer agent were placed in a separable flask. and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 65°C, and reaction was carried out for 3 hours, and then continued at 75°C. It was made to react for 2 hours, and the polymer 2 solution with a solid content concentration of 25 mass % was obtained.

(polymer 3)

As a monomer component, cyclohexyl methacrylate (CHMA): 95 parts by mass, 4-hydroxybutylacrylate (4HBA): 5 parts by mass, ethyl acetate: 300 parts by mass as a polymerization solvent, and 2-mercaptoethanol as a chain transfer agent. (Thioglycol): 3 parts by mass were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 65°C, and reaction was carried out for 3 hours, and then continued at 75°C. It was made to react for 2 hours, and the polymer 3 solution with a solid content concentration of 25 mass % was obtained.

(polymer 4)

As a monomer component, cyclohexyl methacrylate (CHMA): 85 parts by mass, 4-hydroxybutylacrylate (4HBA): 15 parts by mass, ethyl acetate: 300 parts by mass as a polymerization solvent, and 2-mercaptoethanol as a chain transfer agent. (Thioglycol): 3 parts by mass were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 65°C, and reaction was carried out for 3 hours, and then continued at 75°C. It was made to react for 2 hours, and the polymer 4 solution with a solid content concentration of 25 mass % was obtained.

(Polymer 7)

As monomer components, methyl acrylate (MA): 55 parts by mass, N-vinylpyrrolidone: 45 parts by mass, ethyl acetate: 300 parts by mass as a polymerization solvent, and 2-mercaptoethanol (thioglycol) as a chain transfer agent: 3 parts by mass were put into a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a polymerization initiator, the temperature was raised to 65°C, and reaction was carried out for 3 hours, and then continued at 75°C. The reaction was conducted for 2 hours to obtain a polymer 7 solution with a solid content concentration of 25% by mass.

＜Measurement of Tg (℃)＞

It was calculated using the Fox equation according to the above method.

＜Measurement of HSP value＞

It was calculated using the personal computer software HSPiP according to the above method.

[Examples 1 to 21, Comparative Examples 1 to 4]

<Manufacture of adhesive composition>

Using the acrylic polymer solution obtained above as the first polymer, the second polymer obtained above, the second polymer shown below, crosslinking agent, ionic liquid, and additives as shown in Tables 1 to 2, stirring, The adhesive compositions (solutions) for electrical peeling of Examples 1 to 21 and Comparative Examples 1 to 4 were obtained by mixing and adjusting the solid content concentration to 25% by mass. Tables 1 and 2 show the compounding amounts of each component.

In addition, the value of each component in Tables 1 and 2 means parts by mass. In addition, the mixing amount (parts by mass) of the polymer represents the mixing amount (parts by mass) of solid content in the polymer solution.

<Manufacture of electrically peelable adhesive layer>

The adhesive composition (solution) for electrical peeling obtained above was applied to the peeling surface of the polyethylene terephthalate peeling liner (product name "MRF38", manufactured by Mitsubishi Suzy Co., Ltd.) with a peeling surface using an applicator to achieve a uniform thickness. It was applied. Next, heat drying was performed at 150°C for 3 minutes, and the peeled surface of the polyethylene terephthalate release liner (product name "MRE38", manufactured by Mitsubishi Resin Co., Ltd.) was placed on the adhesive layer using a hand roller. By laminating, an electrically peelable adhesive layer (adhesive sheet) with a thickness of 50 μm was obtained.

<Manufacture of single-sided adhesive sheet with base material formed>

The obtained electrically peelable adhesive layer (adhesive sheet) was made into a sheet with a size of 10 mm (manufactured by Co., Ltd., thickness 12 µm, size 10 mm x 100 mm) were bonded together to form a single-sided adhesive sheet with a base formed thereon.

＜Manufacture of conjugate＞

The release liner of the single-sided adhesive sheet with the base material formed is peeled off, and a stainless steel plate (SUS316, size: 30 mm × 120 mm) is placed on the peeled side as an adherend so that one end of the adhesive sheet protrudes from the adherend by about 2 mm. Attach, press in one round with a 2 kg roller, leave for 30 minutes in an environment of 23°C, and form a stainless steel plate (6)/electrically peelable adhesive layer (adhesive sheet) (1')/film with a metal layer (for electric current). A conjugate consisting of (5') was obtained. An outline of the conjugate is shown in Figure 4.

＜Evaluation＞

(180° peel force)

A 180° peel test was conducted using the conjugates of Examples and Comparative Examples. The adherend used was a stainless steel plate (SUS304, size: 30 mm × 120 mm).

Peel in the direction of the arrow in Figure 4 using a peel tester (brand name "Variable Angle Peel Tester YSP", manufactured by Asahi Seiko Co., Ltd.), and obtain the adhesive strength in the 180° peel test (tensile speed: 300 mm/min, peel temperature 23°C). was measured, the 180° peeling force was measured, and this was taken as the initial adhesive force. The measurement results are shown in Tables 1 and 2.

(Initial electric peeling force)

After manufacturing the bonded body by pressing it in one round with a 2 kg roller and leaving it for 30 minutes in an environment at 23°C, before peeling, the negative and positive electrodes of the direct current machine are placed at the points α and β in Figure 4 of the bonded body. were mounted on each, a voltage of 30 V was applied for 30 seconds, and the peel was peeled in the same manner as the above-described 180° peel force measurement while the voltage was still applied, and the adhesive force during voltage application was measured and used as the initial electric peel force. The measurement results are shown in Tables 1 and 2.

In addition, from the initial adhesive force measured above and the adhesive force during voltage application, the rate of decrease in adhesive strength was calculated using the following formula (C). The results are shown in Tables 1 and 2.

Adhesion decline rate (%) = {1 - (adhesion during voltage application/initial adhesion)} × 100 (C)

(Electrical peeling force after moist heat storage)

After pressing in one round with a 2 kg roller, storing in an environment of 60°C, 90% RH for 500 hours, taking out, and leaving for 60 minutes at 22°C, 50% RH to cool down, adhesion was measured. carried out. Before peeling, the negative and positive electrodes of a direct current machine were respectively attached to the points α and β in FIG. 4 of the joint, and a voltage of 30 V was applied for 30 seconds. While applying the voltage as is, the above-described voltage was applied as is. It was peeled in the same manner as the 180° peel strength measurement, and the adhesive strength during voltage application was measured and used as the electric peel strength after moist heat storage. The measurement results are shown in Tables 1 and 2.

The abbreviated names of the second polymer, crosslinking agent, ionic liquid, and additives (adsorption type inhibitor, etc.) in Tables 1 and 2 are as follows.

(second polymer)

Polymer 5: Acrylic polymer, brand name “ARUFON UC3000”, manufactured by Toa Synthetic Co., Ltd.

Polymer 6: Acrylic polymer, brand name “ARUFON UH2170”, manufactured by Toa Synthetic Co., Ltd.

(Tackifying resin)

YS Polystar T-115: Terpene-based tackifying resin, manufactured by Yasuhara Chemical Co., Ltd., Tg = 65°C, softening point 115°C

YS Polystar U-130: Terpene-based tackifying resin, manufactured by Yasuhara Chemical Co., Ltd., Tg = 80°C, softening point 130°C

Pencel D125: Rosin-based tackifying resin, manufactured by Arakawa Chemical Industry Co., Ltd., Tg = 75°C, softening point 125°C

Pencel D160: Rosin-based tackifying resin, manufactured by Arakawa Chemical Industry Co., Ltd., Tg = 110°C, softening point 160°C

(ionic liquid)

AS-110: Cation: 1-ethyl-3-methylimidazolium cation, anion: bis(fluorosulfonyl)imide anion, brand name “Elexel AS-110”, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.

(Cross-linking agent)

V-05: Polycarbodiimide resin, brand name “Carbodilight V-05”, manufactured by Nisshinbo Chemical Co., Ltd.

(Adsorption type inhibitor)

AMINE O: 2-(8-heptadecen-1-yl)-4,5-dihydro-1H-imidazole-1-ethanol, brand name “AMINE O”, manufactured by BASF Japan Co., Ltd.

Irgacor DSSG: Sodium sebacate, brand name “Irgacor DSSG”, manufactured by BASF Japan Co., Ltd.

(Chelate-forming metal deactivator)

Irgamet 30: N,N-bis(2-ethylhexyl)-[(1,2,4-triazol-1-yl)methyl]amine, brand name “Irgamet 30” manufactured by BASF Japan Co., Ltd.

(ionic liquid)

EMIM-MeSO3: manufactured by Tokyo Chemical Industry Co., Ltd.

Since the electrically peelable adhesive layer formed from the adhesive composition of Examples 1 to 21 contains a second polymer having a glass transition temperature (Tg) of 40 to 180°C, it is resistant to application of voltage even after storage in a high temperature and high humidity environment. The rate of decline in adhesion was high and the wet heat stability was excellent. In addition, the electrically peelable adhesive layer formed from the adhesive composition of Examples 15 to 21 further contained a tackifying resin, and further improvement in the rate of adhesive strength decline due to application of voltage after storage in a high temperature and high humidity environment was observed. .

The present invention is not limited to the above-described embodiments, and various changes are possible within the scope indicated in the claims, and embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the present invention. .

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various changes or modifications can be made within the scope described in the claims, and they are naturally understood to fall within the technical scope of the present invention. In addition, each component in the above embodiment may be arbitrarily combined as long as it does not deviate from the spirit of the invention.

In addition, this application is based on a Japanese patent application (Japanese Patent Application No. 2022-026640) filed on February 24, 2022 and a Japanese patent application (Japanese Patent Application No. 2021-161475) filed on September 30, 2021. and the contents thereof are incorporated by reference in this application.

X1, X2, X3: Adhesive sheets
1: Electrically peelable adhesive layer
2: Adhesive layer
3: Description
4: conductive layer
5: Base material for conducting electricity

Claims (14)

An adhesive composition containing a first polymer and an ionic liquid,
Comprising the first polymer as a base polymer,
An adhesive composition further comprising a second polymer having a glass transition temperature (Tg) of 40 to 180°C. According to claim 1,
An adhesive composition wherein the HSP value difference between the first polymer and the second polymer is 0 to 3. According to claim 1,
An adhesive composition in which the second polymer contains an organic polymer compound, and the content of the organic polymer compound in the second polymer is 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer. According to claim 1,
An adhesive composition wherein the anion of the ionic liquid contains at least one selected from the group consisting of bis(fluorosulfonyl)imide anion and bis(trifluoromethanesulfonyl)imide anion. According to claim 1,
An adhesive composition in which the cation of the ionic liquid contains at least one selected from the group consisting of a nitrogen-containing onium cation, a sulfur-containing onium cation, and a phosphorus-containing onium cation. According to claim 1,
The adhesive composition wherein the content of the ionic liquid is 0.5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the first polymer. According to claim 1,
The first polymer is an adhesive composition comprising at least one member selected from the group consisting of polyester polymer, urethane polymer, and acrylic polymer having a carboxyl group, an alkoxy group, a hydroxyl group, and/or an amide bond. According to claim 1,
A pressure-sensitive adhesive composition, wherein the second polymer comprises a tackifying resin. According to claim 8,
A pressure-sensitive adhesive composition wherein the softening point of the tackifying resin is 100° C. or higher. According to claim 8,
The adhesive composition wherein the content of the tackifying resin is 1 to 50 parts by mass with respect to 100 parts by mass of the first polymer. According to claim 8,
A pressure-sensitive adhesive composition wherein the tackifier resin is a terpene-based tackifier resin or a rosin-based tackifier resin. According to claim 1,
Adhesive composition for electrical peeling. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 12. Equipped with the adhesive sheet according to claim 13 and a conductive material,
A bonded body in which the adhesive layer is adhered to the conductive material.